"candidates" is the word i'm focusing on here. And in all black hole sighting reports. It's not that i disbelieve the black hole theory, it's just that that is still what it is currently. [gosh i hope i'm right about that, wiki says i'm right ]

I wonder if we will ever understand them enough to know what happens to all that matter. If they are grouped together into a cluster of sorts, does that mean they might eventually swallow each other up?

I wonder if we will ever understand them enough to know what happens to all that matter. If they are grouped together into a cluster of sorts, does that mean they might eventually swallow each other up?

Some theorize that this is how the ultra-huge supermassive black holes form.

I would guess this means there are no equivalent clusters in our own galaxy? And that the extra radiation, especially when they collide, might perhaps mean that the chances of there being a place to live in that area is pretty small?

I would guess this means there are no equivalent clusters in our own galaxy? And that the extra radiation, especially when they collide, might perhaps mean that the chances of there being a place to live in that area is pretty small?

Hard to say... but it's a lot easier to observe things like this in other galaxies. It's sort of like trying to see what's in a huge mansion-like house when you're inside of it and can't move out of the little corner of the room you're stuck in.

It's a lot easier to look out the window at the neighbor's similar mansion and see what's in theirs.

I would guess this means there are no equivalent clusters in our own galaxy? And that the extra radiation, especially when they collide, might perhaps mean that the chances of there being a place to live in that area is pretty small?

Nonsense. There are people living all over the universe (and by people I don't mean humans from Earth). They would just have to live further out from the central core, or be a form that isn't affected by extra radiation. Either that or Earth is the only place in the universe where life exists.

It's really all just hypothetical for now. Might as well go with more exciting of the two hypotheses.

I would guess this means there are no equivalent clusters in our own galaxy? And that the extra radiation, especially when they collide, might perhaps mean that the chances of there being a place to live in that area is pretty small?

Places to live for whom? Us? I never know how to interpret statements like this. There are so many presuppositions...

Life itself can handle radiation, both in terms of known bacterial life on earth and in terms of technological advancements that could outfit humans with radiation resistant "skin" or something, these seem likely given given time. So maybe "humans of today" is meant. But what is meant by that because it would take 2.5 million years to get there (roughly) traveling at a speed we believe is impossible to attain?

So we would have to be magically transported there for the question to make sense.

Or perhaps the writer is wrapping in a presupposition about the possibility of complex life developing in such a radiation bathed zone. Perhaps he has equations that show that the radiation would be so powerful as to make complex molecules impossible. Or something. I don't know because he didn't say.

EDIT: Or perhaps a theory about panuniversal humanism is silently held, and then it becomes obvious that if life is on a trajectory to humanhood, and that we ourselves and our ancestors could not have withstood the radiation levels in that area, that matter could not have exactly recapitulated its embedded pull towards life as we know it as *we know it must*.

THIS COULD MEAN THE END OF SPACE AS WE KNOW IT! Considering the enormity of the cosmos, by comparison... not very much... knowing I mean. Also too, the farther we see into it, the further into the past we see.

Each of the black holes is of the kind that forms after a star collapses in on itself.

What are the other kinds that you are trying to differentiate from, and how are they visibly different?

It is not known how supermassive black holes form, and it may well not be from a stellar black hole progenitor. That is one theory, but the seed might also have been formed directly during the Big-Bang, or from enormous "quasi"-stars before the first true stars. There is some evidence that there is a different formation mechanism, which is the fact that there is a huge mass-gap between the two types. The largest known stellar black holes are about 33 solar masses... and the smallest supermassive BH is over 200,000 solar masses. Where are the intermediate forms, if one forms from the other?

I'd guess the objects in Andromeda are part of that answer. After all, it is not much younger than the Milky Way, and has quite a few smallish black holes near its core. I expect they will all merge eventually.

I'd guess the objects in Andromeda are part of that answer. After all, it is not much younger than the Milky Way, and has quite a few smallish black holes near its core. I expect they will all merge eventually.

That is possible; I think it is quite likely personally. That wasn't my point; my point is that pixelstuff seemed to disparage the idea that there could be a black hole that didn't come from a stellar collapse, and I was calling that out.

I would guess this means there are no equivalent clusters in our own galaxy? And that the extra radiation, especially when they collide, might perhaps mean that the chances of there being a place to live in that area is pretty small?

I suppose you could say this cluster of black holes near the edge of the central bulge makes it unprecedentedly inhospitable?

The central bulge is generally expected to be inhospitable due to the relatively high concentration of intense radiation and gravitational sources - aka massive old/dead stars. There are obvious and persistent sources of radiation such as pulsar; those massive old stars in general and the density at which they occur also represent an obstacle to planet formation as well as a threat to the stability of orbital systems. More significant might be the the type 1a supernovae; more stars per unit volume means more binary systems per unit volume which in turn means more type 1a supernovae per unit-volume per unit time that are more likely to occur at close distances. Though less common, there's also the type 2 supernovae which would pose an existential threat to organized matter in general over a relatively large area.

Just to be clear, when one describes the proximity of these kinds of sources of radiation as being inhospitable to life this not the same sense as terrestrial sources of radiation being damaging to cell structure. Type 1a supernova for example could be estimated to be a threat to terrestrial life at perhaps 33 light years distance - radiation that would kill life we are familiar with but not threaten the very presence of organized matter. At the proximity and frequency at which binary systems which are type 1a candidates occur in central galactic bulges however, it means that there are regions in which it is exceedingly improbable that complex systems could form due to the irregular yet relatively frequent bombardment by intense radiation and gravitational sheering. Evolution requires replication with random variation and attrition, but in this case attrition would occasionally include the irregular but repeated sudden transition of all solid matter into a super-heated gas.

That is not to say that there may not be regions of relative calm and low density within and around a central bulge or that by inhospitable to life one means impossible. It is just that the probability of conditions which preclude the persistence of complex organized matter is not small and their frequency could be expected to be relatively often on a geologic time scale.

So in addition to the conditions we had previously expected to be typical of a large spiral bulge, this relatively high density of black holes with companion stars outside of the bulge itself would indicate an even greater density and frequency of events/conditions which would preclude the formation of complex systems let alone familiar forms of life.

So what about black hole in our galaxy? When are we going to get sucked up? It seems like that may be more important to us?

The supermassive black-hole in the center of our galaxy, Sagittarius A, does not actually consume very much matter on average. Recent observations have show that the halo of super-hot gasses falling towards and currently observed just above its event horizon produce such great outward pressure that 99.9% of the material outside this region is repelled rather than ultimately falling into it.

So it is effectively denied a significant steady diet of interstellar gas and dust. While it may occasionally manage to gobble up something large from collisions, the supernova-like explosions such events produce as something like a star was compressed and distorted as it falls towards the event horizon would similar propel much of that mass outward before it ever reached the event horizon while also briefly intensifying the pushing away of the nearby interstellar medium.

Without a significant mechanism to expand, it is not reasonably possible for it to threaten to swallow the Earth let alone very much of the matter relatively close to it. As it is now, the threat of it swallowing the galaxy is about as likely as the Sun swallowing Neptune.

Mind you, Sagittarius A may not be typical of most super-massive black holes in the centers of galaxies. It is relatively small compared to the estimated size of some other prospective galactic core black holes - which recent observations have suggested may swallow 1 Sun's worth of mass per year. By comparison, the gas cloud in an acretion trajectory towards Sagittarius A* is only roughly 3 times the mass of the Earth and would represent a comparative binge period even if most of it isn't repelled. As of 2009 it has shown signs of being disrupted and dispersed by the intense pressures as it approaches closer.

...since the chance of either hypothesis being true is 50/50, as in "there either is extraterrestrial life, or there isn't". /s

You forgot "was" and "will be". The odds that there were never any extraterrestrial life, isn't, and never will be seem quite remote.

I think it would be quite possible in the not so far future for us to send automated probes out to near-ish planets and then get from one, however many years later, transmissions showing pictures of alien ruins.

Seriously, people, black holes don't "suck" in the way that you imagine a vacuum cleaner. Like all objects in the universe, they simply collect matter through the everyday force of gravity. It just happens that since black holes have the mass of a star compacted in a single point in space, the force of gravity get really friggin strong if you get too close to that point. For instance, if the Earth magically turned into a black hole with the mass of the Earth, all of the satellites would still orbit around Black Hole Earth. The moon and the ISS would keep moving in their respective orbits. The problem becomes that if you hit reverse thrusters and let gravity pull you down, then you're pretty much screwed because you're now entering a singularity. So, in conclusion, just don't get too close that you cannot escape gravity and you're fine. This goes for all black holes. They're just point source with mass and gravity.

Also, the reason we see these candidate black holes is because of the matter accreting onto them. The gas forms an accretion disk which glows because it's heated and has a very specific spectral signature that astronomers can identify.